Processes for controlling afterburn in a reheater and for controlling loss of entrained solid particles in combustion product flue gas

Abstract

Processes for controlling afterburn in a reheater and loss of entrained solid particles in reheater flue gas are provided. Carbonaceous biomass feedstock is pyrolyzed using a heat transfer medium forming pyrolysis products and a spent heat transfer medium comprising combustible solid particles. The spent heat transfer medium is introduced into a fluidizing dense bed. The combustible solid particles of the spent heat transfer medium are combusted forming combustion product flue gas in a dilute phase above the fluidizing dense bed. The combustion product flue gas comprises flue gas and solid particles entrained therein. The solid particles are separated from the combustion product flue gas to form separated solid particles. At least a portion of the separated solid particles are returned to the fluidizing dense bed.

Description

FIELD OF THE INVENTION[0001]The present invention generally relates to processes for controlling combustion in a reheater of a pyrolysis system, and more particularly relates to a process for controlling afterburn in the reheater and controlling loss of entrained solid particles in combustion product flue gas during regeneration of a heat transfer medium.DESCRIPTION OF RELATED ART[0002]Pyrolysis is a thermal process during which solid carbonaceous biomass feedstock, i.e., “biomass”, such as wood, agricultural wastes / residues, algae, forestry byproducts, cellulose and lignin, municipal waste, construction / demolition debris, or the like, is rapidly heated to pyrolysis temperatures of about 300° C. to about 900° C. in the absence of air using a pyrolysis reactor. Biomass may be pyrolyzed using various pyrolysis methods, including the Rapid Thermal Process and catalytic pyrolysis. Under these conditions, solid, liquid, and gaseous pyrolysis products are formed. The gaseous pyrolysis pro...

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